The present invention relates to a radio-frequency (RF) transmission method, a magnetic resonance imaging (MRI) apparatus, and an auxiliary coil. More particularly, the present invention is concerned with an RF transmission method, an MRI apparatus, and an auxiliary coil which make it possible to intensify the strength of a magnetic field to be applied to a subject.
In a magnet assembly included in a typical MRI apparatus, a body coil, an RF shield, gradient coils, and a main magnetic field generation magnet are disposed in that order from the side of a bore, which is an imaging space, of the magnet assembly to the external side thereof (refer to, for example, Patent Documents 1 and 2).
[Patent Document 1] Japanese Unexamined Patent Publication No. 2000-116619
[Patent Document 2] Japanese Unexamined Patent Publication No. 2004-248928
A bore that is an imaging space in an MRI apparatus has a large inner diameter that is large enough to accommodate even a huge subject (patient). There is a distance between a body coil incorporated in a magnet assembly and a subject.
However, if there is a distance between a transmitter coil and a subject, the strength of a magnetic field to be applied to the subject is so feeble that a large power is needed to transmit RF pulses from the body coil so as to excite the subject.